had the energy of 15 000 tons of TNT (18 million kWh). A megaton bomb
delivers an energy of 1.2 billion kWh. If dropped on a city of one million,
a megaton bomb makes an energy donation of 1200 kWh per person,
equivalent to 120 litres of petrol per person. The total energy of the USA’s
nuclear arsenal today is 2400 megatons, contained in 10 000 warheads. In
the good old days when folks really took defence seriously, the arsenal’s
energy was 20 000 megatons. These bombs, if used, would have delivered
an energy of about 100 000 kWh per American. That’s equivalent to 7 kWh
per day per person for a duration of 40 years – similar to all the electrical
energy supplied to America by nuclear power.

Energy cost of making nuclear materials for bombs

The main nuclear materials are plutonium, of which the USA has produced
104 t, and high-enriched uranium (HEU), of which the USA has produced
994 t. Manufacturing these materials requires energy.

The most efficient plutonium-production facilities use 24 000 kWh of
heat when producing 1 gram of plutonium. So the direct energy-cost of
making the USA’s 104 tons of plutonium (1945–1996) was at least 2.5 tril-
lion kWh which is 0.5 kWh per day per person (if shared between 250
million Americans).

The main energy-cost in manufacturing HEU is the cost of enrichment.
Work is required to separate the 235U and 238U atoms in natural uranium in
order to create a final product that is richer in 235U. The USA’s production
of 994 tons of highly-enriched uranium (the USA’s total, 1945–1996) had
an energy cost of about 0.1 kWh per day per person.

“Trident creates jobs.” Well, so does relining our schools with asbestos,
but that doesn’t mean we should do it!

Marcus Brigstocke

Universities

According to Times Higher Education Supplement (30 March 2007), UK
universities use 5.2 billion kWh per year. Shared out among the whole
population, that’s a power of 0.24 kWh per day per person.

So higher education and research seem to have a much lower energy
cost than defensive war-gaming.

There may be other energy-consuming public services we could talk
about, but at this point I’d like to wrap up our race between the red and
green stacks.

Figure 17.1. The energy cost of defence in the UK is estimated to be about 4 kWh per day per person.